Back to EveryPatent.com
United States Patent |
5,622,488
|
Tojo
,   et al.
|
April 22, 1997
|
Scroll type fluid machine having first and second frame members to
increase air tightness
Abstract
A scroll type compressor having high efficiency and high reliability is
obtained by preventing leakage of a compression chamber, increasing air
tightness thereof and securing a smooth motion of an orbiting scroll
member. A second frame member supported by a first frame member and
slightly movable in the axial direction is disposed in the rear of an
orbiting scroll member. Force is applied to the rear of the second frame
member, and a slight axial movement of the orbiting scroll member is
regulated by a fixed scroll member and the second frame member. As a
result, both the scroll members are in tight contact or close to each
other with a small space, and a smooth movement thereof can be secured,
which makes it possible to obtain a scroll type compressor having high
efficiency and high reliability.
Inventors:
|
Tojo; Kenji (Shimizu, JP);
Ueda; Hideyuki (Shimizu, JP);
Mizuno; Takao (Shimizu, JP);
Hida; Takeshi (Shimizu, JP)
|
Assignee:
|
Hitachi, Ltd. (Tokyo, JP)
|
Appl. No.:
|
515333 |
Filed:
|
August 15, 1995 |
Foreign Application Priority Data
Current U.S. Class: |
418/55.5; 418/57 |
Intern'l Class: |
F01C 001/04 |
Field of Search: |
418/55.5,57
|
References Cited
U.S. Patent Documents
5277563 | Jan., 1994 | Wen-Jen et al. | 418/55.
|
5340287 | Aug., 1994 | Kawamura et al. | 418/55.
|
5342186 | Aug., 1994 | Swain | 418/55.
|
Foreign Patent Documents |
63-80088 | Apr., 1988 | JP.
| |
Primary Examiner: Freay; Charles G.
Attorney, Agent or Firm: Antonelli, Terry, Stout & Kraus, LLP
Claims
What is claimed is:
1. A scroll type fluid machine, comprising a fixed scroll member and an
orbiting scroll member each having an end plate and a scroll wrap portion
standing perpendicular to said end plate, wherein said orbiting scroll
member is connected to a driver through a main shaft, and said above
components are housed in a hermetic case, said scroll type fluid machine
further comprising a first frame member positioned on the opposite side of
said orbiting scroll member to the wrap portion side thereof, rotatably
supporting said main shaft and fixed to said hermetic case, and a second
frame member provided between said first frame member and said orbiting
scroll member to be given a gas pressure for pressing said orbiting scroll
member toward said fixed scroll member, and an orbiting scroll rear
chamber provided as an airtight space, to which pressure in a compression
chamber defined by said fixed scroll member and said orbiting scroll
member in the middle of compression is led, on the inner periphery of said
second frame member to press said orbiting scroll member toward said fixed
scroll member.
2. A scroll type fluid machine according to claim 1, wherein said orbiting
scroll member has a hole for communicating said orbiting scroll rear
chamber and said compression chamber defined by said fixed scroll member
and said orbiting scroll member during compression.
3. A scroll type fluid machine according to claim 2, further comprising a
second frame rear chamber provided as an airtight space, to which
discharge pressure is led, between said second frame member and said first
frame member to press said second frame member toward said orbiting scroll
member.
4. A scroll type fluid machine according to claim 3, wherein said first
frame member has a hole for communicating said second frame rear chamber
and a lower space of said hermetic case to be given discharge pressure.
5. A scroll type fluid machine according to claim 1, wherein a contact
plane is provided between said fixed scroll member and said second frame
member to regulate the amount of movement of said second frame member
toward said orbiting scroll member.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scroll type fluid machine, and more
particularly, to a scroll type compressor suitably used as a refrigerant
compressor of an air conditioner and a refrigerator, and as an air
compressor.
2. Description of the Related Art
In a conventional scroll type compressor, a fixed scroll member and an
orbiting scroll member, each composed of an end plate and a scroll wrap
portion standing perpendicular to the end plate, are meshed with the wrap
portions inside and the orbiting scroll member is driven by a main shaft
directly connected to a motor or the like to make revolution, by which
refrigerant gas is sucked into a compression chamber formed by both the
scroll members, the compression chamber is moved to a central portion to
reduce the volume thereof and increase the pressure therein, and the
refrigerant gas is exhausted from a discharge port in the central portion
therein.
In such a scroll type compressor, compression is performed by meshing both
the scroll wrap portions with each other, and setting of the positions of
these wrap portions in the vertical direction is considerably important.
If wider spaces than needed are formed between the leading ends of the
wrap portions and the opposed end plates, the refrigerant gas leaks from
the spaces to the low pressure side, thereby lowering the performance of
the compressor. Furthermore, if the leading ends of the wrap portions are
in excessively strong contact with the corresponding end plates, galling
and wear are caused and interfere with smooth compression.
Still further, since the gas in the compression chamber has a force which
separates the scroll members from each other in the axial direction, there
is provided a mechanism for keeping, against this separating force, both
the scroll members in tight contact or slightly spaced.
For example, Japanese Patent Unexamined Publication No. 63-80088 discloses
a closed scroll type compressor which increases the pressure of a
refrigerant gas, led into a hermetic case, by compression and directly
discharges the refrigerant gas to the outside of the hermetic case. In
this compressor, a thrust bearing is provided in the rear of an end plate
in an orbiting scroll member, a fixed scroll member is fixed to the
hermetic case through a pair of leaf springs, and an airtight chamber is
formed in the rear of the fixed scroll member. Gas pressure is applied to
the airtight chamber to slightly move the fixed scroll member in the axial
direction thereof, and to minimize the space between wrap portions of the
scroll members, by which leakage of a compression chamber can be
prevented.
However, in such a structure, the whole thrust force in the axial direction
applied to the orbiting scroll member by compressing the refrigerant gas
acts on the thrust bearing. Furthermore, when the fixed scroll member is
slightly moved toward the orbiting scroll member against the spring force
of the leaf springs by exerting the gas pressure on the rear of the fixed
scroll member, a force, which is obtained from deducting a reaction force
of the leaf springs from the gas pressure applied to the rear of the fixed
scroll member, further presses the orbiting scroll member in the axial
direction, and therefore, the thrust bearing receives greater force.
Accordingly, an expensive thrust bearing resistant to a heavy thrust load
is needed, and frictional force is caused by the slide between the thrust
bearing and the rear of the end plate in the orbiting scroll member, which
results into large sliding loss, lowered efficiency of the compressor, and
abrasion, burning and the like of the aforesaid sliding portion.
Further, in such a structure, a complicated structure is required to move
the fixed scroll member in the axial direction, to avoid excessive contact
and abutment between the wrap portions of the fixed scroll member and the
orbiting scroll member, and to prevent the displacement of center shafts
and phases of both the scroll wrap portions. This causes various problems,
for example, decrease in productivity and decrease in efficiency and
reliability owing to excessive contact.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a scroll type compressor
which reduces leakage of a compression chamber defined by an orbiting
scroll member and a fixed scroll member by improving air tightness of the
compression chamber.
In order to achieve the above object, there is provided a scroll type fluid
machine comprising a fixed scroll member and an orbiting scroll member
each having an end plate and a scroll wrap portion standing perpendicular
to the end plate, wherein the orbiting scroll member is connected to a
driver with a main shaft, gas is discharged from a discharge port, and
these components are housed in a hermetic case, the scroll type fluid
machine further comprising a first frame member positioned on the opposite
side of the orbiting scroll member to the wrap portion side thereof,
rotatably supporting the main shaft and fixed to the hermetic case, and a
second frame member provided between the first frame member and the
orbiting scroll member to receive a gas pressure for pressing the orbiting
scroll member toward the fixed scroll member.
The function of the present invention having the above-mentioned structure
is as follows.
The second frame member supported by the first frame member and capable of
moving slightly in the axial direction is located on the opposed side of
the orbiting scroll member to the wrap portion side thereof, and the
second frame member and the fixed scroll member restrict the axial slight
movement of the orbiting scroll member. When pressure is applied to an
airtight space formed in the rear of the second frame member, the second
frame member slightly moves toward the orbiting scroll member and slides
on the rear surface of the orbiting scroll member, thereby restricting the
axial movement of the orbiting scroll member. The orbiting scroll member
is in tight contact with or close with a slight space to the fixed scroll
member to thereby avoid leakage of the compression chamber defined by the
orbiting scroll member and the fixed scroll member. Therefore, it is
possible to obtain a scroll type compressor having high efficiency and
high reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal cross sectional view of a closed scroll type
compressor according to an embodiment of the present invention;
FIGS. 2A and 2B show a first frame member, FIG. 2A being a plan view and
FIG. 2B a longitudinal cross sectional view;
FIGS. 3A and 3B show a second frame member, FIG. 3A being a plan view, and
FIG. 3B a longitudinal cross sectional view;
FIG. 4 is a longitudinal cross sectional view of a closed scroll type
compressor according to another embodiment of the present invention; and
FIGS. 5A and 5B show a second frame member according to another embodiment
of the present invention, FIG. 5A being a plan view and FIG. 5B a
longitudinal cross sectional view.
DESCRIPTION OF PREFERRED EMBODIMENTS
The preferred embodiments of the present invention will be described below
with reference to FIGS. 1 to 5. FIG. 1 is a longitudinal cross sectional
view of a closed scroll type compressor according to an embodiment of the
present invention, FIGS. 2A and 2B are respectively plan and longitudinal
cross sectional views of a first frame member shown in FIG. 1, FIGS. 3A
and 3B are respectively plan and longitudinal cross sectional views of a
second frame member shown in FIG. 1, FIG. 4 is a longitudinal cross
sectional view of a closed scroll type compressor according to another
embodiment of the present invention, and FIGS. 5A and 5B are respectively
plan and longitudinal cross sectional views of a second frame member shown
in FIG. 4.
As shown in FIG. 1, a hermetic case 10 accommodates a compression mechanism
section and a motor section. Although a motor is used as a driver in this
embodiment, other driver may be used instead of the motor. The compression
mechanism section includes an orbiting scroll member 1, a fixed scroll
member 2, a rotation preventing member 3, a main shaft 4 for driving the
orbiting scroll member 1, a first frame member 5 for supporting these
components, and the like. The fixed scroll member 2 is composed of an end
plate 2a and a wrap portion 2b standing perpendicular to the end plate 2a.
The fixed scroll member 2 further includes an intake port 2c and a
discharge port 2d. The orbiting scroll member 1 comprises a disc end plate
1a, a wrap portion 1b standing perpendicular to the end plate 1a, and a
concave boss 1c formed on the surface opposed to the wrap portion 1b (rear
surface). The wrap portions 1b and 2b of the scroll members 1 and 2 each
have the shape of an involute curve or a similar curve. The fixed scroll
member 2 and the orbiting scroll member 1 are meshed with each other so
that the wrap portions 1b and 2b thereof are opposed to each other.
The first frame member 5 rotatably supports the main shaft 4, connected to
a motor 7 at one end thereof, through a bearing portion provided in the
center thereof. The outer peripheral surface of the first frame member 5
is joined to the inner wall of the hermetic case 10. The main shaft 4
rotatably supported by the bearing portion of the first frame member 5 is
connected to the motor 7 at one end, and an eccentric portion thereof is
engaged with the boss 1c of the orbiting scroll member 1. An oil feed hole
41 is formed inside the main shaft 4 from the end of the eccentric portion
throughout the length of the main shaft 4 to feed oil collecting in the
hermetic case 10 to the aforesaid engaging portion.
An airtight chamber (orbiting scroll rear chamber 11) is formed on the
surface of the orbiting scroll member 1 opposite to the wrap portion (rear
surface) by the end plate 1a of the orbiting scroll member 1 and the first
frame member 5. The orbiting scroll rear chamber 11 and a compression
chamber formed by the scroll members 1 and 2, in which compression is
being performed, communicate with each other through a communicating hole
1d formed through the end plate 1a of the orbiting scroll member 1.
In the rear of the orbiting scroll member 1, the rotation preventing member
(Oldham's ring) 3 is provided to prevent rotation of the orbiting scroll
member 1 on its axis.
Furthermore, a second frame member 6 supported by the first frame member 5
and capable of slightly moving in the axial direction is disposed in the
rear of the orbiting scroll member 1. The axial movement of the orbiting
scroll member 1 in the wrap direction (vertically upward) is regulated by
the fixed scroll member 2, and the movement thereof in the rear direction
(vertically downward) is regulated by the second frame member 6.
In the scroll type compressor having such a structure, the orbiting scroll
member 1 is revolved relative to the fixed scroll member 2 by the action
of the main shaft 4 and the rotation preventing member 3 in correlation to
the rotation of the motor 7. As the compression chamber defined by the
orbiting and fixed scroll members 1 and 2 moves toward those central
portion, the volume thereof decreases, by which a refrigerant gas sucked
from the intake port 2c into the compression chamber is compressed and
discharged from the discharge port 2d into the upper portion of the
hermetic case 10. The refrigerant gas discharged into the upper portion of
the hermetic case 10 is passed through paths 5a formed on the outer
periphery of the first frame 5 shown in FIG. 2A, sent to the lower portion
of the hermetic case 10, and discharged to the outside through a discharge
pipe 15.
Lubricating oil is stored at the bottom of the hermetic case 10 and sent to
the engaging portion between the main shaft 4 and the bearing portion of
the first frame member 5 and the engaging portion between the main shaft 4
and the boss 1c of the orbiting scroll member 1 through the oil feed hole
41 formed inside the main shaft 4, thereby lubricating the engaging
portions. The lubricating oil led to the engaging portions is discharged
into the orbiting scroll rear chamber 11 and the hermetic case 10. The
lubricating oil discharged into the orbiting scroll rear chamber 11 is
used to lubricate the sliding portion between the second frame member 6
and the orbiting scroll member 1 or the rotation preventing member 3, or
led from the communicating hole 1d formed in the orbiting scroll member 1
or from the outer periphery of the orbiting scroll member 1 into the
compression chamber defined by both the scroll members 1 and 2 to be used
to seal the sliding portion of both the scroll members 1 and 2 or the
compression chamber. After the completion of compression, the lubricating
oil is discharged from the discharge port 2d into the hermetic case 10
together with the refrigerant gas and stored at the bottom of the hermetic
case 10.
Since the airtight chamber (orbiting scroll rear chamber) 11 provided in
the rear of the orbiting scroll member 1 communicates with the compression
chamber defined by the scroll members 1 and 2, in which compression is
being performed, through the communicating hole 1d, the pressure in the
orbiting scroll rear chamber 11 is kept between an intake pressure and a
discharge pressure.
On the other hand, a pressure almost equal to the discharge pressure or
between the intake pressure and the discharge pressure is led to an
airtight chamber (second frame rear chamber) 12 supported by the first
frame member 5 and formed in the rear of the second frame member 6 movable
in the axial direction (the discharge pressure is applied through an
intake hole 5b in this embodiment), and kept at least higher than the
pressure in the orbiting scroll rear chamber 11.
As a result, the second frame member 6 moves in the axial direction and
slides in contact with the rear surface of the orbiting scroll end plate
1a, thereby pressing the orbiting scroll member 1 against the fixed scroll
member 2 and restricting the axial movement of the orbiting scroll member
1.
An axial force acting on the rear surface of the orbiting scroll member 1
is the sum of the force of the second frame member 6, the pressure of the
lubricating oil, almost equal to the discharge pressure, acting on the
inside of the boss 1c in the orbiting scroll member 1, and the pressure in
the orbiting scroll rear chamber 11.
On the other hand, an axial force resulting from the pressure in the
compression chamber defined by both the scroll members 1 and 2 is exerted
on the orbiting scroll member 1 in a direction for separating the scroll
members 1 and 2.
Therefore, a force which overcomes the force acting vertically downward
resulting from the pressure in the compression chamber is applied to the
rear surface of the orbiting scroll member 1, the orbiting scroll member 1
is slightly moved in the axial direction, and put into tight contact with
the fixed scroll member 2. The pressure in the orbiting scroll rear
chamber 11 is determined as desired by the pressure receiving area of the
orbiting scroll end plate 1a in the orbiting scroll rear chamber 11 and
the position of the communicating hole 1d communicating with the
compression chamber in the middle of compression. The force acting on the
rear surface of the second frame member 6 can be also set at a desired
value by changing the pressure receiving area of the second frame member 2
occupied in the second frame rear chamber 12 or leading the discharge
pressure or the pressure in the compression chamber in the middle of
compression.
As a result, it is possible to secure a smooth movement of the orbiting
scroll member 1, to keep air tightness of the compression chamber defined
by the orbiting scroll member 1 and the fixed scroll member 2, and to
maintain high efficiency.
Another embodiment is shown in FIGS. 4 and 5. In the embodiment shown in
FIG. 4, slight axial movement of a second frame member 6 supported by a
first frame member 5 is regulated by a seat portion 6a (shown in FIGS. 5A
and 5B) of the second frame member 6 and a bearer surface of the fixed
scroll member 2 in contact with the seat portion 6a. Specifically, the
second frame member 6 is moved toward the scroll members 1 and 2
(vertically upward) by the pressure applied to a second frame rear chamber
12, and stopped at the point at which the seat portion 6a abuts against
the bearer surface of the fixed scroll member 2. As a result, the orbiting
scroll member 1 is prevented from moving in the axial direction and
sandwiched with a small space by the fixed scroll member 2 and the second
frame member 6.
When the sum of the pressure acting on the orbiting scroll rear chamber 11
in the rear of the orbiting scroll member 1 and the pressure of
lubricating oil, almost equal to the discharge pressure, acting on the
inside of the boss 1c of the orbiting scroll member 1 is larger than the
axial separating force resulting from the pressure in the compression
chamber and acting on the wrap side of the orbiting scroll member 1, the
orbiting scroll member 1 is pressed and put into tight contact with the
fixed scroll member 2 to thereby make revolution. On the other hand, if
the sum of the above axial forces is smaller than the separating force,
the rear surface of the orbiting scroll member 1 slides on the second
frame member 6 while keeping a slight space between the orbiting scroll
member 1 and the fixed scroll member 2, which makes it possible to avoid
excessive contact between the orbiting scroll member 1 and the fixed
scroll member 2 and to obtain a scroll type compressor having high
efficiency and high reliability.
Although the pressure in the hermetic case is equal to the discharge
pressure and the pressure in the orbiting scroll rear chamber 11 is kept
between the intake pressure and the discharge pressure in the above
embodiments, the present invention is not limited to the structures shown
in the embodiments. The present invention includes a case in which the
pressure in the hermetic case is equal to the discharge pressure and the
pressure in the orbiting scroll rear chamber is equal to the intake
pressure. Similar function and advantageous effects can be also obtained
in this case.
According to the present invention, when a slight axial movement of the
second frame member is regulated by the seat portion thereof to be abutted
against the fixed scroll member, the orbiting scroll member can move with
a slight space relative to the fixed scroll member. Therefore, it is
possible to avoid excessive contact between the orbiting scroll member 1
and the fixed scroll member 2 and to obtain a scroll type compressor
having high efficiency and high reliability.
If the pressure in the compression chamber is extremely increased by
mixture of a large amount of liquid refrigerant or oil therein and exceeds
the pressure to be applied to the second frame member 2, the orbiting
scroll member presses down the second frame member toward the rear of the
orbiting scroll member (vertically downward), moves slightly in the
rearward direction (vertically downward), and the space between the wrap
portions of the fixed scroll member and the orbiting scroll member is
increased to leak the gas, the liquid refrigerant or the oil from the high
pressure side to the low pressure side, thereby avoiding excessive
increase in pressure.
According to the present invention, it is possible to prevent leakage of
the compression chamber defined by the orbiting scroll member and the
fixed scroll member, and to obtain a scroll type compressor which is
excellent in efficiency and reliability.
Top